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An isomer of B20H26, isolated from the autolysis of nido-B10H14 in a silent electrical discharge, is shown to be the title compound 1,1'-bis(nido-decaboranyl). The mol­ecule has crystallographic inversion symmetry and a long intercage B-B bond of 1.704 (3) Å.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101003407/br1315sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101003407/br1315Isup2.hkl
Contains datablock I

Comment top

Some time ago, the synthesis of the globular macropolyhedral megaloborane B20H26, from the passage of B10H14 through a silent electrical discharge, was reported, although precise reaction conditions were unspecified (Friedman et al., 1963). An alternative Me2BNHMe-catalysed thermolytic preparation was also reported (Miller & Muetterties, 1963; Miller et al., 1964). Since then (Miller & Muetterties, 1963, Enemark et al., 1966), this very interesting compound has been essentially unexamined. We have now developed an interest in B20H26 and in the possibilities of synthesizing other globular boranes (Kaur et al., 1997; Bould et al., 1999, 2000, Yao et al., 1999), and have consequently sought to duplicate the original synthesis that used a silent electrical discharge. A 1500 V AC silent discharge through a glass tube containing decaborane(14) yielded predominantly a yellow material which is a main focus of our investigations and which we have yet to identify. However, dichloromethane extraction of the material followed by high-performance liquid chromatographic (HPLC) separation yielded very small quantities of several substances, shown by NMR spectroscopy to be a variety of boron hydride species. Predominant among these was a series of compounds identified by NMR spectroscopy (compare with Boocock et al., 1980) as being in the bis(nido-decaboranyl) family, (B10H13)2. Two of these were identified as the known compounds, i.e. 2,2'- and 1,2'-(nido-B10H13)2 (after Boocock et al., 1981). A further previously unobserved bis(nido-decaboronyl) isomer was isolated and crystallized by slow sublimation in an evacuated tube. We report here its structure determination as the 1,1'-(nido-B10H13)2 isomer, i.e. the title compound. Crystals were small (0.03 mm micron cubes) and the single-crystal work required synchrotron-generated X-irradiation for sufficient diffraction intensity (Cernik et al., 1997, 2000; Clegg et al., 1998).

There are 15 possible isomers of (nido-B10H13)2, of which eight are four enantiomeric pairs (Boocock et al., 1980). Those previously characterized structurally by single-crystal X-ray work are the 1,2'- (Barrett et al., 1985), the 1,5'- (Brown et al., 1979), the 2,2'- and the 2,6'- species (Boocock et al., 1980). The 6,6'- (Boocock et al., 1979), 2,5'- and 5,5'-isomers (Boocock et al., 1981) have been characterized by NMR spectroscopy. The 1,1'-isomer (Fig. 1) contains an inversion centre in the midpoint of the intercage B—B linkage. The B—B linkage distance [B1—B1i; symmetry code: (i) 1 - x, 1 - y, 1 - z] of 1.704 (3) Å is at the top end of the range of values for reported bis(decaboranyl) isomers, which range from 1.698 (2) (1,5'-isomer; Brown et al., 1979) to 1.679 (3) Å (2,2'-isomer; Barrett et al., 1985). The basal intracluster B—B distances associated with the linkage B1 atom show small but significant lengthenings of ca 0.017 (2) Å compared to those around the unsubstituted B3 atom and are similar in magnitude to those noted previously (0.015 Å; Boocock et al., 1980). Other distances on the substituted side of the decaborane subcluster do not differ significantly from those on the unsubstituted side with the exception of the long B5—B10 `gunwale' interboron vector in the nido-decaboronyl `boat', which, at 1.955 (2) Å, is 0.016 (2) Å shorter than the opposing B7—B8 distance.

Related literature top

For related literature, see: Barrett et al. (1985); Boocock et al. (1979, 1980, 1981); Bould et al. (1999, 2000); Brown et al. (1979); Cernik et al. (1997, 2000); Clegg et al. (1998); Enemark et al. (1966); Friedman et al. (1963); Kaur et al. (1997); Miller & Muetterties (1963); Miller et al. (1964); Yao et al. (1999).

Experimental top

Decaborane(14) (0.472 g), contained in a small sample vial, was placed in a glass high-voltage silent-discharge reaction tube [constructed in a similar manner to the one used by Friedman et al. (1963)]. Silent electrical discharge under dynamic vacuum (1500 V AC, ca 10-3 mm Hg) for 90 min resulted in a substantial amount of yellow material being deposited on the sides of the tube. The reaction vessel was opened to air and the material extracted with dichloromethane. The extract was filtered through silica gel and the filtrate subjected to preparative high-performance liquid chromatograpic (HPLC) separation (25 × 2.12 cm column, Lichosorb SI 60, 15:85 CH2Cl2/n-hexane, 20 ml min-1) giving three products with RT 6.9 (component A), 7.3 (component B) and 7.7 m (component C). Components A and B were identified by 11B NMR spectroscopy as 2,2' and 1,2'-(nido-B10H13)2, respectively, by comparison with previously characterized samples (Boocock et al., 1981). The 11B NMR spectroscopic characterization of component C suggested the previously unreported 1,1'-bis-decaboranyl isomer; CDCl3 solution 300 K, cluster resonances ordered as, assignment δ(11B)/p.p.m. [2J(11B–1H)/Hz in brackets]: B2,4 - 34.5 [156]; B5,7,8,10 + 0.8 [148]; B6,9 + 9.5 [165]; B3 + 12.8 [151]; B1 + 19.8 [site of conjuncto linkage]. Single crystals were grown over a period of 2 months by sublimation in a sealed evacuated glass tube placed on a warm oven.

Refinement top

Data collection procedures are described by Clegg et al. (1998). The data set, derived from several series of exposures, is complete to θ = 26°. Corrections were applied for the decay in the synchrotron primary beam intensity. All H atoms were refined freely [B—H range 1.051 (16)–1.329 (17) Å].

Computing details top

Data collection: SMART (Siemens, 1997); cell refinement: SAINT (Siemens, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1998); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and local programs.

Figures top
[Figure 1] Fig. 1. The crystallographically determined molecular structure of 1,1'-(nido-B10H13)2 drawn with 40% probability ellipsoids and with H atoms shown as small circles of arbitrary radii.
1,1'-bis(nido-decaboranyl) top
Crystal data top
B20H26Dx = 0.983 Mg m3
Mr = 242.41Synchrotron radiation, λ = 0.6890 Å
Orthorhombic, PbcaCell parameters from 5421 reflections
a = 10.6601 (5) Åθ = 2.7–29.4°
b = 10.5515 (5) ŵ = 0.04 mm1
c = 14.5604 (6) ÅT = 150 K
V = 1637.75 (13) Å3Cuboid, colourless
Z = 40.03 × 0.03 × 0.03 mm
F(000) = 504
Data collection top
Siemens SMART CCD
diffractometer
1746 reflections with I > 2σ(I)
Radiation source: Daresbury SRS station 9.8Rint = 0.056
Silicon 111 monochromatorθmax = 29.4°, θmin = 2.7°
ω rotation with narrow frames scansh = 1414
10589 measured reflectionsk = 147
2301 independent reflectionsl = 2020
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.056Hydrogen site location: difference Fourier map
wR(F2) = 0.150All H-atom parameters refined
S = 1.09 w = 1/[σ2(Fo2) + (0.074P)2 + 0.3725P]
where P = (Fo2 + 2Fc2)/3
2301 reflections(Δ/σ)max < 0.001
143 parametersΔρmax = 0.38 e Å3
0 restraintsΔρmin = 0.18 e Å3
Crystal data top
B20H26V = 1637.75 (13) Å3
Mr = 242.41Z = 4
Orthorhombic, PbcaSynchrotron radiation, λ = 0.6890 Å
a = 10.6601 (5) ŵ = 0.04 mm1
b = 10.5515 (5) ÅT = 150 K
c = 14.5604 (6) Å0.03 × 0.03 × 0.03 mm
Data collection top
Siemens SMART CCD
diffractometer
1746 reflections with I > 2σ(I)
10589 measured reflectionsRint = 0.056
2301 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0560 restraints
wR(F2) = 0.150All H-atom parameters refined
S = 1.09Δρmax = 0.38 e Å3
2301 reflectionsΔρmin = 0.18 e Å3
143 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
B10.46647 (12)0.55218 (12)0.46270 (9)0.0164 (3)
B20.55859 (14)0.67977 (13)0.41826 (10)0.0202 (3)
H20.6587 (16)0.6820 (15)0.4308 (11)0.031 (4)*
B30.49222 (14)0.56719 (14)0.34216 (9)0.0203 (3)
H30.5547 (17)0.5096 (18)0.3019 (11)0.038 (5)*
B40.35058 (13)0.49886 (13)0.38247 (9)0.0187 (3)
H40.3340 (15)0.3996 (15)0.3736 (10)0.023 (4)*
B50.44334 (14)0.70690 (14)0.50513 (10)0.0216 (3)
H50.4615 (15)0.7348 (16)0.5758 (11)0.028 (4)*
B60.47698 (15)0.81984 (15)0.41677 (12)0.0271 (3)
H60.5098 (16)0.9159 (16)0.4290 (12)0.035 (5)*
B70.48766 (15)0.72877 (15)0.31286 (11)0.0258 (3)
H70.5337 (16)0.7655 (16)0.2549 (12)0.033 (4)*
B80.34977 (16)0.60858 (15)0.28909 (11)0.0269 (3)
H80.3291 (16)0.5832 (15)0.2190 (12)0.036 (5)*
B90.22848 (14)0.60423 (15)0.37348 (11)0.0257 (3)
H90.1329 (15)0.5890 (15)0.3596 (11)0.030 (4)*
B100.30692 (13)0.58756 (14)0.48119 (10)0.0210 (3)
H100.2541 (14)0.5530 (14)0.5389 (10)0.023 (4)*
H110.3832 (18)0.7963 (17)0.4698 (13)0.044 (5)*
H120.4106 (16)0.8139 (16)0.3396 (12)0.035 (5)*
H130.2693 (17)0.6912 (16)0.3154 (11)0.038 (5)*
H140.2419 (18)0.6740 (16)0.4456 (12)0.043 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
B10.0164 (6)0.0165 (6)0.0164 (6)0.0014 (5)0.0010 (4)0.0013 (5)
B20.0209 (7)0.0161 (6)0.0235 (7)0.0002 (5)0.0003 (5)0.0009 (5)
B30.0240 (7)0.0198 (7)0.0170 (6)0.0006 (5)0.0017 (5)0.0004 (5)
B40.0201 (6)0.0168 (6)0.0192 (6)0.0008 (5)0.0027 (5)0.0008 (5)
B50.0236 (7)0.0190 (7)0.0224 (7)0.0047 (5)0.0022 (5)0.0042 (5)
B60.0267 (7)0.0194 (7)0.0351 (8)0.0013 (6)0.0033 (6)0.0002 (6)
B70.0272 (7)0.0227 (8)0.0275 (7)0.0002 (6)0.0012 (6)0.0075 (6)
B80.0315 (8)0.0261 (8)0.0232 (7)0.0015 (6)0.0077 (6)0.0036 (6)
B90.0219 (7)0.0221 (7)0.0333 (8)0.0021 (5)0.0073 (6)0.0001 (6)
B100.0190 (6)0.0219 (7)0.0221 (6)0.0031 (5)0.0005 (5)0.0004 (5)
Geometric parameters (Å, º) top
B1—B1i1.704 (3)B5—B101.955 (2)
B1—B101.7620 (19)B5—H51.088 (16)
B1—B51.7628 (19)B5—H111.251 (18)
B1—B31.7836 (19)B6—B71.796 (2)
B1—B21.788 (2)B6—H61.087 (17)
B1—B41.7910 (19)B6—H111.288 (19)
B2—B61.715 (2)B6—H121.329 (17)
B2—B31.772 (2)B7—B81.972 (2)
B2—B51.787 (2)B7—H71.051 (18)
B2—B71.787 (2)B7—H121.278 (17)
B2—H21.083 (17)B8—B91.784 (2)
B3—B71.758 (2)B8—H81.077 (17)
B3—B81.759 (2)B8—H131.282 (17)
B3—B41.773 (2)B9—B101.786 (2)
B3—H31.075 (18)B9—H91.051 (16)
B4—B91.717 (2)B9—H131.321 (17)
B4—B101.777 (2)B9—H141.290 (17)
B4—B81.786 (2)B10—H101.075 (15)
B4—H41.070 (15)B10—H141.258 (18)
B5—B61.790 (2)
B1i—B1—B10116.40 (12)B2—B6—B561.24 (8)
B1i—B1—B5115.71 (12)B2—B6—B761.15 (9)
B10—B1—B567.37 (8)B5—B6—B7105.19 (10)
B1i—B1—B3128.32 (12)B2—B6—H6129.6 (9)
B10—B1—B3106.26 (9)B5—B6—H6124.6 (9)
B5—B1—B3106.51 (10)B7—B6—H6128.1 (9)
B1i—B1—B2119.14 (13)B2—B6—H11102.7 (8)
B10—B1—B2115.21 (10)B5—B6—H1144.3 (8)
B5—B1—B260.42 (8)B7—B6—H11116.8 (8)
B3—B1—B259.49 (8)H6—B6—H11109.4 (12)
B1i—B1—B4120.14 (13)B2—B6—H12103.9 (7)
B10—B1—B460.02 (8)B5—B6—H12118.0 (7)
B5—B1—B4115.02 (10)B7—B6—H1245.3 (7)
B3—B1—B459.48 (8)H6—B6—H12110.8 (11)
B2—B1—B4112.29 (9)H11—B6—H1294.8 (11)
B6—B2—B3111.54 (11)B3—B7—B259.96 (8)
B6—B2—B561.45 (9)B3—B7—B6108.43 (11)
B3—B2—B5106.00 (10)B2—B7—B657.20 (8)
B6—B2—B761.65 (9)B3—B7—B855.91 (8)
B3—B2—B759.21 (8)B2—B7—B8106.26 (10)
B5—B2—B7105.70 (10)B6—B7—B8116.40 (11)
B6—B2—B1112.02 (11)B3—B7—H7122.6 (9)
B3—B2—B160.14 (8)B2—B7—H7126.8 (9)
B5—B2—B159.10 (8)B6—B7—H7120.6 (9)
B7—B2—B1107.24 (10)B8—B7—H7116.4 (9)
B6—B2—H2118.9 (8)B3—B7—H12128.7 (8)
B3—B2—H2120.9 (8)B2—B7—H12102.3 (8)
B5—B2—H2123.7 (8)B6—B7—H1247.7 (8)
B7—B2—H2123.7 (8)B8—B7—H1291.5 (8)
B1—B2—H2119.8 (8)H7—B7—H12106.6 (12)
B7—B3—B868.21 (9)B3—B8—B9108.47 (10)
B7—B3—B260.83 (8)B3—B8—B460.03 (8)
B8—B3—B2116.94 (11)B9—B8—B457.49 (8)
B7—B3—B4116.81 (11)B3—B8—B755.88 (8)
B8—B3—B460.74 (8)B9—B8—B7115.84 (11)
B2—B3—B4113.93 (10)B4—B8—B7106.24 (10)
B7—B3—B1108.70 (10)B3—B8—H8122.1 (9)
B8—B3—B1108.75 (10)B9—B8—H8119.8 (9)
B2—B3—B160.37 (8)B4—B8—H8124.1 (9)
B4—B3—B160.47 (7)B7—B8—H8118.6 (9)
B7—B3—H3115.6 (10)B3—B8—H13128.0 (8)
B8—B3—H3115.8 (9)B9—B8—H1347.7 (8)
B2—B3—H3118.2 (10)B4—B8—H13102.5 (7)
B4—B3—H3118.6 (10)B7—B8—H1390.5 (8)
B1—B3—H3125.6 (9)H8—B8—H13108.4 (12)
B9—B4—B3110.92 (10)B4—B9—B861.30 (9)
B9—B4—B1061.45 (8)B4—B9—B1060.94 (8)
B3—B4—B10106.06 (10)B8—B9—B10105.54 (10)
B9—B4—B861.21 (9)B4—B9—H9130.6 (9)
B3—B4—B859.23 (8)B8—B9—H9125.0 (9)
B10—B4—B8105.85 (10)B10—B9—H9127.4 (9)
B9—B4—B1111.67 (10)B4—B9—H13104.4 (8)
B3—B4—B160.05 (8)B8—B9—H1345.8 (8)
B10—B4—B159.18 (7)B10—B9—H13118.4 (8)
B8—B4—B1107.23 (10)H9—B9—H13107.6 (12)
B9—B4—H4120.0 (8)B4—B9—H14102.9 (8)
B3—B4—H4119.9 (8)B8—B9—H14117.7 (9)
B10—B4—H4124.7 (8)B10—B9—H1444.7 (8)
B8—B4—H4122.8 (8)H9—B9—H14110.6 (13)
B1—B4—H4120.0 (8)H13—B9—H1495.0 (11)
B1—B5—B260.48 (8)B1—B10—B460.80 (8)
B1—B5—B6109.67 (10)B1—B10—B9109.80 (10)
B2—B5—B657.31 (8)B4—B10—B957.61 (8)
B1—B5—B1056.29 (7)B1—B10—B556.34 (7)
B2—B5—B10106.38 (9)B4—B10—B5106.78 (9)
B6—B5—B10116.72 (10)B9—B10—B5116.20 (10)
B1—B5—H5123.9 (9)B1—B10—H10123.6 (8)
B2—B5—H5126.2 (9)B4—B10—H10126.2 (8)
B6—B5—H5117.7 (9)B9—B10—H10118.3 (8)
B10—B5—H5118.4 (9)B5—B10—H10118.0 (8)
B1—B5—H11128.7 (9)B1—B10—H14128.5 (9)
B2—B5—H11100.5 (9)B4—B10—H14101.1 (8)
B6—B5—H1146.0 (9)B9—B10—H1446.2 (8)
B10—B5—H1191.8 (9)B5—B10—H1490.9 (8)
H5—B5—H11106.0 (12)H10—B10—H14106.3 (12)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaB20H26
Mr242.41
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)150
a, b, c (Å)10.6601 (5), 10.5515 (5), 14.5604 (6)
V3)1637.75 (13)
Z4
Radiation typeSynchrotron, λ = 0.6890 Å
µ (mm1)0.04
Crystal size (mm)0.03 × 0.03 × 0.03
Data collection
DiffractometerSiemens SMART CCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
10589, 2301, 1746
Rint0.056
(sin θ/λ)max1)0.712
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.056, 0.150, 1.09
No. of reflections2301
No. of parameters143
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.38, 0.18

Computer programs: SMART (Siemens, 1997), SAINT (Siemens, 1997), SAINT, SHELXTL (Sheldrick, 1998), SHELXTL and local programs.

Selected geometric parameters (Å, º) top
B1—B1i1.704 (3)B3—B81.759 (2)
B1—B101.7620 (19)B3—B41.773 (2)
B1—B51.7628 (19)B4—B91.717 (2)
B1—B31.7836 (19)B4—B101.777 (2)
B1—B21.788 (2)B4—B81.786 (2)
B1—B41.7910 (19)B5—B61.790 (2)
B2—B61.715 (2)B5—B101.955 (2)
B2—B31.772 (2)B6—B71.796 (2)
B2—B51.787 (2)B7—B81.972 (2)
B2—B71.787 (2)B8—B91.784 (2)
B3—B71.758 (2)B9—B101.786 (2)
B1i—B1—B10116.40 (12)B1i—B1—B2119.14 (13)
B1i—B1—B5115.71 (12)B1i—B1—B4120.14 (13)
B1i—B1—B3128.32 (12)
Symmetry code: (i) x+1, y+1, z+1.
 

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